The field of the invention is cleaning apparatus for cleaning carriers or containers used to hold and process semiconductor wafers, substrates, flat panel displays and similar flat articles or workpieced requiring low contamination levels.
The processing of semiconductor wafers, substrates, photomasks, flat panel displays, data disks, optical media and other articles relating to the semiconductor industry (collectively referred to here as xe2x80x9cwafersxe2x80x9d) is very sensitive to contamination. These articles or wafers require extremely low contamination levels. Even microscopic particles can cause defects in the articles or the devices made from them. Accordingly, it is necessary to maintain a high level of cleanliness during virtually all manufacturing steps.
Semiconductor wafers are typically processed in batches. Batch handling may occur throughout the entire production process, or for one or more processing steps or related handling operations. Batch processing almost always uses some type of carrier, container, or box (collectively referred to here as a carrier) to hold the wafers. The wafer carriers can be of various designs. In box types of carriers, the wafers are held and enclosed against contamination during travel within the processing facility. Other carriers are open, to allow process liquids or gases to contact the wafers held by the carrier. The wafer carriers must be cleaned, to avoid having particles and contaminants on the carriers contaminate the wafers. However, cleaning wafer carriers can be difficult because they typically have features such as slots, grooves, corners, openings, etc.
One type of wafer carrier is known as the front opening unified pod, or FOUP. A FOUP carrier has a five-sided box with an open front. A door attaches to the front of the box, to seal the box against entry of external contaminants, to help keep the wafers clean. FOUPs or other carriers may be designed to hold 200 mm or 300 mm wafers. Consequently, their larger sizes coupled with the features described above, can make cleaning them even more difficult. The FOUP doors may also be difficult to clean, as they have interior hollow areas which may not be directly accessible via conventional spray cleaning techniques, and because they may tend to trap and hold cleaning liquids. Accordingly, improved apparatus and techniques are needed for cleaning carriers.
Carriers have been successfully cleaned in centrifugal cleaners. See, for example, U.S. Pat. No. 5,738,128 and Ser. No. 09/611,642, filed Jul. 7, 2000, incorporated herein by reference. In the centrifugal cleaners shown in U.S. Pat. No. 5,738,128, the box or carrier is loaded onto a rotor, with the open top or front side of the box facing radially outwardly from the rotor. The box is then sprayed with cleaning fluids, and then with drying gases, while the rotor turns. Centrifugal force helps to remove cleaning fluids from the box, to help dry it. While these techniques have worked well for different types of carriers and boxes, achieving better and more reliable cleaning remains as an engineering design challenge.
In a first aspect of the invention, an apparatus for cleaning a wafer carrier includes a rotor carrying five sided boxes. The open side of the box faces radially outwardly. Spray manifolds have straight spray nozzles and angled spray nozzles. The straight spray nozzles provide a spray towards the center of the rotor and directly into the box. The angled spray nozzles, oriented towards and/or away from the spin direction, are better positioned to spray leading and/or trailing surfaces, corners, and features of the box. This results in improved cleaning.
In a second aspect, spray manifolds are provided having angle spray nozzles directed at up and/or down angles.
Other and further objects, inventive features, and advantages, will appear hereinafter. The invention resides as well in subsystems and subcombinations of the features described. The features of the various embodiments described may be used with any embodiment, and not only with the specific embodiment on which they are shown or described. It is an object of the invention to provide improved cleaning apparatus and methods.